Yes,
I had a similar problem when building it. The front of the firewall cracked and collapsed or sucked in as I was sinking the blind nuts to back of firewall. I basically had to use a different mount than was shipped with model, I mounted an Saito 100 which required a different mount. This required that I patch the holes that I had made for the original mount and these original holes is where the fiberglass over the firewall was collapsing in as the blind nuts were being sucked in from the back. This resulted in some cracking of the fiberglass. I worked with this and studied it for several day since I was very concerned about it. At the end of the day it seems that the firewall plywood behind the fiberglass seems stable other that it is splintering a bit and blind nuts dont want to stay. I have had 2 flights so far and I seel no further deterioration. I did have to re tighten the bolts holding the engine mount to the firewall and I CA the cracks and indentations on the from and got a good amount of epoxy inside the fuse around the outside of the firewall to harden it up a bit more. I hope it does not deteriorate any further. The new mount I used for the SAITO had a smaller bolt patter, closer to center of firewall than mount shipped with the kit. Seemed to be more stability in this area of firewall. I think in manufacture they got some air or space between plywood firewall and the glass.